Many eyes will be on Energy and Natural Resources Chairwoman Mary L. Landrieu as the Senate gears up for another debate over the fate of the Keystone XL pipeline from Canada.

She's taking on President Barack Obama and most of her Democratic Party as she faces a tight re-election race back home in Louisiana, hoping for a win on the pipeline and an energy efficiency bill to boot.

"If everyone cooperates we just might be able to get an efficiency bill that both parties have worked on, very hard, and it’s very important, will create a lot of jobs in our country, on an important part of our energy mix, and we may also be able to get a vote on Keystone," Landrieu said Wednesday.

But her Republican Senate counterpart from Louisiana may throw a wrench into the process, with David Vitter again floating a contentious amendment eliminating health benefits for lawmakers and congressional staff. House Republicans from Louisiana, including Landrieu challenger Bill Cassidy, sent a letter Monday to Landrieu, the chairwoman of the Energy and Natural Resources Committee, and ranking member Lisa Murkowski, R-Alaska, seeking support for legislation to bypass the Obama administration.

"We can no longer trust the President and Senator Reid to make the best decision for the American people on this issue," the lawmakers wrote. "The President has not signed energy legislation into law and Senator Reid has not allowed a vote on energy legislation in the U.S. Senate for over 4 years. We encourage you to quickly move this or similar legislation through the Senate as soon as possible."

Republican aides think falling short of the 60 votes that would undoubtedly be needed to advance the pipeline approval amendment could hurt Landrieu. The Democrat has touted her influence as the new chairwoman of the energy panel as among the reasons Louisianans should return her to the Senate this fall.

At this point, the vote looks like it would be too close for comfort on both sides.

"We have made a decision that we do some kind of separate vote on Keystone," he said.

Schumer acknowledged that Democrats had plans for a nonbinding measure on the pipeline issue. But that clearly became untenable to Republicans after the State Department moved to indefinitely delay the process.

Sen. John Hoeven, R-N.D., who is involved in the negotiations, said backers are close to the 60 votes they need.

"I think we are at about 56, right in that range," Hoeven said. "We have another six or seven who have said maybe."

Hoeven said the amendment would approve the pipeline, taking the decision out of the administration’s hands.

A stand-alone Keystone bill could be vetoed by Obama without dooming the energy efficiency bill.

White House Press Secretary Jay Carney was asked about Keystone Wednesday and said the approval has to be done "by the book" and said politics should not enter the decision.

Vitter announced Wednesday he would again seek to offer an amendment that would effectively eliminate the employer contribution to health insurance plans for members of Congress and their staffs, as well as prevent certain senior officials from getting health care tax credits for purchasing insurance on the exchanges established under the Affordable Care Act.

"Americans are struggling with the ongoing Obamacare train wreck every day. They're losing the coverage they liked, seeing their premiums skyrocket, and finding it hard to enroll in anything new," Vitter said. "But what makes it even worse is that while all this is going on, Washington elites have carved out a special exemption and subsidy for themselves."

Reid blasted Vitter's amendment, saying it would be unfair for staffers to not get employer-sponsored health care like other full-time employees. He suggested Vitter could derail the entire agreement on the energy efficiency bill.

"I guess he had such a good time a year ago," Reid said. "Maybe he wants to kill energy efficiency again."

Asked if Vitter's latest move makes it more difficult to work with him, she replied, "It's always difficult."

"I don't understand anything about what he's doing," Landrieu said.

And Sen. Mark Begich, D-Alaska, who, like Landrieu, faces a tough re-election and wants a binding vote on the pipeline, urged Vitter to stand down.

"If you want to fix [Obamacare] there are all kinds of ideas that we can work on. But let's work on energy next week. ... It's important to his state, my state and Keystone is one that we should be able to get to a possibility here. But he needs to get off of Obamacare."

A senior Democratic aide said it would be up to Portman and GOP leadership to corral members seeking to offer terribly extraneous amendments. Republicans have been practically salivating for a big energy policy debate, saying Reid has blocked it for years.

Portman said he hopes Vitter will abstain too.

"We should keep the amendments to the broad and important field of energy, and there's plenty of energy-related issues that we should debate," he said.

The other energy-related amendments could make for difficult votes, too. Hoeven said that the deal also would include allowing GOP amendments to Shaheen-Portman, including opposing coal regulations and boosting liquid natural gas exports.

Geof Koss and Steven T. Dennis contributed to this report.

Correction: May 1, 2:23 p.m. An earlier version misidentified the state Sen. John Hoeven, R-N.D., represents.